The present invention is a filiform ultrasound catheter, in stainless steel, whose distal end is formed by a bulb-shaped catheter tip, that is substantially spherical, coated with a diamond coating.
The objective of conventional angioplasty procedures using balloon catheters for dilation, is to restore the lumen of arteries that are partially obstructed or occluded by blood clots and/or atheroma. For this purpose, vascular surgeons and intervention radiologists pass a balloon catheter through the residual arterial lumen, inflate the balloon to flatten the atheroma against the arterial wall, which enables blood circulation to be restored. A stent may then be inserted to reduce the risk of recurrent stenosis.
If the said balloon catheter cannot be passed through the said stenosis: either because the diameter of the said residual arterial lumen is too narrow; or because there is total occlusion; or because there are calcified plaques of atheroma; or because stenosis is multiple, the sole remaining solution is a bypass procedure to replace the damaged segment of the atheromatous artery with a natural or artificial prosthesis. Bypass procedure entails a heavy, traumatizing operation with risks related to heavy surgery that it is preferable to avoid whenever possible.
Precisely, ultrasound transluminal angioplasty systems, due to the effect of ultrasound on atheroma, restore the possibility of conducting conventional angioplasty by widening the said diameter of the residual arterial lumen or by tunneling through the stenosis.
Alternatively, reamers can be used for angioplasty. These systems using diamond-tipped reamers rotating around a metal guide have very high rotating speeds. For this reason, and due to their inertia, when their movement is set in motion these said diamond-tipped reamers draw the metal guide towards pathways of non-zero radius around the guide before stabilizing themselves in normal operating position to attack the stenosis. Deprived of guidance, the pathway of these rotating reamers is no longer controlled, and this excursive tendency to move over wider pathways is even further accentuated. It is during these excursions that the diamond-tipped reamers carry the danger of injuring the arterial wall in particular in arteries of narrow diameter. Ultrasound catheters, on the other hand, since they operate by longitudinal vibration in relation to the metal guide, are not subject to this tendency to follow a pathway away from the guide and to damage the arterial wall. These ultrasound catheters offer better security for the arterial wall.
The present invention brings the following advantages:
1) Compared with conventional filiform ultrasound catheters, whose catheter tip does not have a diamond coating, it is more effective in attacking the calcified, hardened plaques of atheroma without reducing its efficacy in breaking up other biological tissues.
2) The size of the diamond grains set in the diamond coating is such that very small debris is produced which can be easily removed by aspiration or through natural routes.
3) Compared with angioplasty systems using rotating diamond-tipped reamers, it entails lesser risk of injuring the arterial wall.
The present invention pertains to a wire-shaped ultrasonic catheter for ultrasonic angioplasty. The ultrasonic catheter head is provided with a diamond coating. The catheter has a cylindrical sonotrode and a thin ultrasound catheter which together form a resonant system. The catheter is made from a thin stainless steel ultrasound waveguide. The catheter is coupled to a mechanical connection system at one end and at the other end to a hardened, bulb-shaped stainless steel catheter tip having a cylindrical, spherical or rounded conical shape with a diamond powder coating.